A grating 3D (namely, three-dimensional) display device mainly comprises: a display screen and a grating superimposed on the front or back of the display screen. The display screen includes a plurality of sub-pixels arranged in a matrix. The grating includes light-blocking strips and light-transmitting strips, which are alternately arranged. Upon 3D display being performed, a left-eye image signal is applied to half of the sub-pixels of the display screen and a right-eye image signal is applied to the other half of the sub-pixels; and the sub-pixels applied with the left-eye image signal and the sub-pixels applied with the right-eye image signal are alternately arranged along a row direction.
When a person views a display image at an appropriate position, because there is a certain distance between a left eye and a right eye, namely the viewing angle of the left eye and the viewing angle of the right eye are different, and the light-blocking strips of the grating have a certain blocking function on the sub-pixels, the left eye can only receive light passing through the sub-pixels applied with the left-eye image signal and the right eye can only receive light passing through the sub-pixels applied with the right-eye image signal, and hence the left-eye image light and the right-eye image light are separated in space. Because a left-eye image and a right-eye image are images captured from different angles, the left-eye image and the right-eye image are superimposed in the brain, and hence the 3D display effect can be produced.